The millimeter wave spectrum is the frequency band of spectrum between 30 GHz and 300 GHz. This spectrum can be used for high-speed wireless communications as seen with the latest IEEE 802.11ad Wi-Fi standard (operating at 60 GHz).
V-Band is a set of millimeter wave frequencies used for communication. Regulatory authorities in some countries permit unlicensed V-Band operation. The set of frequencies over which unlicensed V-Band operation is permitted in the U.S. is currently 57 to 71 GHz. Standards applicable to V-Band communications include IEEE 802.11ad (released 28 Dec. 2012) and IEEE 802.11ay (currently under development).
E-Band is another set of millimeter wave frequencies usable for communication. Regulatory authorities, e.g., the Federal Communications Commission (FCC), generally permit lightly-licensed operation in this band. In the U.S., E-Band operation is permitted in the following frequency bands of 71-76, 81-86, and 92-95 GHz.
The FCC also regulates numerous other unlicensed bands, including Industrial, Scientific, and Medical (ISM) bands at approximately 2 GHz and 6 GHz and other frequencies. In recent years, some of the fastest-growing uses of the ISM bands and other lightly licensed or unlicensed bands have been for short-range, low-power wireless communications systems, referred to commonly as WiFi.
A problem with some wireless networks, particularly those operating at millimeter wave frequencies, is the ability for wireless signals to penetrate obstructions, such as walls or floors within buildings or other barriers. Although millimeter-wave signals can and do pass through some obstructions, they are often degraded by doing so. Degradation may be due to attenuation, reflection and other physical processes caused by the obstruction. As frequency of transmission increases, attenuation by obstacles and free space also increases. The result is a reduction of received power, thereby limiting signal range and ability to penetrate obstructions.
Another issue is that in some systems, the millimeter-wave signals are highly directional, relatively narrow beams that do not spread over an expansive region.